Falling behind on the track (8)
I believe the answer is:
trailing
This clue might be a double definition.
'falling behind' is the first definition.
(trailing is a kind of falling behind)
'the track' is the second definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'on' is the link.
Can you help me to learn more?
(Other definitions for trailing that I've seen before include "Lagging behind or tracking" , "falling behind in race" , "Chasing after" , "Lagging behind in a race" , "at the back" .)